There could be a number of problems as to why there is oil in your radiator and it is important to be aware that your engine will have a serious problem if this happens. Arguably the most common cause is a blown head gasket which runs through the upper and lower sections of the engine.
The lower section, also known as the block, contains the pistons and crankshaft whereas the upper section also called the head holds the engine valves. The gasket which holds the sections together has holes in it which allows the engine coolant to circulate around the upper and lower sections as well as holes for oil to flow through. If the gasket blows, the engine oil will enter the coolant passages causing the engine to fail.
Moreover, damage to the cylinder connected to the engine block may cause the oil to seep into the radiator. The bolts that hold the cylinder head onto the engine block can sometimes experience wear and stretching which destroys the seal on the head gasket. Therefore, the oil and coolant will be forced to mix together after flowing into the gasket.
In addition, if the engine overheats then the cylinder head could get warped and cause the same problem. If a crack appears between the internal oil and coolant passages within the engine block then a problem will occur. The cracks can develop due to a strong impact such as a crash or by the engine freezing which can occur in bitterly cold conditions. Freezing can also occur if too much water is in the antifreeze or coolant mixture which could make it expand and crack.
It all depends on what type oil is in the water. If it is motor oil, you may have a head gasket blown or leaking and about to blow. If it is transmission fluid, the transmission cooler built into the radiator may have a leak in it. Trahsmissione fluid in the water should have a red color to it. If it is motor oil it should have a milky look, usually on the bottom side of the radiator cap. Either problem needs fixed, if it is tranny fluid in the radiator replace the radiator soon, you don't want the water to get into the tranny.
Sounds like if theres no water in your oil then you have a busted cooling line inside your radiator try and make sure it is oil are transmission fluid either way you probly need a new radiator also if its transmission fluid you need your transmission cleaned out and a new filter if its oil then clean out reso vore and heater core and coolant hoses when you replace radiator
I have a 1997 old cutlass supreme
there is oil in the radiator but no antifreeze in oil whats the problem
Make sure that its oil in coolant system and not transmission liquid caused from a busted radiator
HAVE oil in radiator on 96 grand prix had it checked no blown head gasket, what else could it be? The car only has 70,000 miles on it.
To the person who put water in the coolant reservoir: This is really not a problem. You normally have a 50/50 mix of antifreeze and water in the cooling system. A little extra water won't hurt. Before freezing temperatures next winter have your antifreeze tested at a repair shop just to be sure that it is not too diluted. (This is normally a free service.)
Your head gasket is leaking, I am sorry, depending on what kind of car it is, it could be expensive.
By mistake I put water in coolant reservoir what you advise me to do
Blown head gasket or cracked head
Did he have the head machined? If not it problem is blow again.
You might a cracked block.
Oil in radiator might be a blown head gasket
Sounds like you have either ring problems or a warped head. Either way it my be expensive to repair. Might consider replacing the engine with a good used one from one of the salvage yards nearby.....